Letter to the Editor (other)

doi:10.1093/rheumatology/keu426

Screening psoriatic arthritis tools: analysis of theEarly Arthritis for Psoriatic Patients questionnaire

SIR, PsA is a chronic, seronegative inflammatory arthritis

associated with psoriasis. Early diagnosis and treatment

are needed, since the disease can lead to irreversible

changes (such as erosive arthritis), which lead to perman-

ent physical disability and deformity. Recent studies have

shown that PsA is often overlooked in patients with psor-

iasis. Reich et al. [1] studied 1511 patients with psoriasis,

and found 17.5% patients who were newly diagnosed

with PsA. In a further study including 2009 patients with

psoriasis, 4.2% were newly diagnosed with PsA.

Recently, Haroon et al. [2] reported 29% newly diagnosed

PsA in patients with psoriasis.

Psoriasis presents before arthritis in the majority of pa-

tients; therefore, dermatologists are ideally placed to

make an early diagnosis. Several screening tools for iden-

tifying PsA in patients with psoriasis have been developed

in the last decade [3�6]. These are questionnaires based

on items related to symptoms and signs of PsA and

appear to have good sensitivity and specificity in their re-

spective development studies. These questionnaires do

not replace a comprehensive musculoskeletal evaluation

(or a decision on treatment) by a rheumatologist, but they

help to increase the detection of PsA in psoriasis patients

and reduce the number of patients needing assessment

by the rheumatologist.

The CONTEST study [7] was carried out with the aim of

comparing three of the known PsA screening question-

naires in the same population. In this study, questions

from PsA screening tools, Psoriatic Arthritis Screening

and Evaluation [5], Toronto Psoriatic Arthritis Screen [3]

and Psoriasis Epidemiology Screening Tool (PEST) [4],

and patients’ answers were stored in a database;

sensitivity and specificity of these questionnaires were

then calculated and compared. Little difference was

found between these questionnaires: notably specificity

was low for all three instruments. A new screening ques-

tionnaire, the Early Arthritis for Psoriatic Patients (EARP)

has recently been developed [8]. The aim of our present

study was to analyse the sensitivity and specificity of the

EARP questionnaire compared with the questionnaires

contained in the CONTEST study database as a fast initial

analysis to establish the feasibility of performing a second

analysis to test this new questionnaire in a real cohort of

patients with PsA.

The first step was to translate the 10 items from the

EARP questionnaire from the original Italian into English.

The translation was done according to the Isis Outcomes

of translation and linguistic validation process developed

at the University of Oxford. The translation consisted of

the following steps: a forward translation was done inde-

pendently by two native Italian speakers, who translated

the Italian questionnaire into English; a reconciled version

was produced from the two forward translations by the

main investigator; this reconciled English version was

back-translated into Italian independently by two transla-

tors (the last two translators had not seen the original

Italian questionnaire); the back translations we reviewed

against the source version to highlight any discrepancies.

The 10 translated questions of the English version of the

EARP were: Do you have pain in your joints? Did you take

any anti-inflammatories more than twice a week in the last

3 months? Do you wake up at night because of back

pain? Do you feel your hands are stiff in the morning for

more than 30 minutes? Do your fingers and wrists hurt?

Are your fingers and wrists swollen? Have you ever no-

ticed a finger swollen like a sausage for more than 3

days? Is your Achilles tendon swollen? Do you have

pain in your feet and ankles? Do you have pain in your

hip or elbow?

The next step was to perform an exploratory analysis

comparing the questions comprising our last English

translation of the EARP with the ones stored in the

CONTEST database. One of the EARP questions (Did

you take any anti-inflammatories more than twice a

week in the last 3 months?) could not be addressed, but

similarly asked questions for the other nine were available

in CONTEST: these were taken from each of the other

questionnaires, as appropriate, and the anatomical loca-

tion questions were taken from the manikin in the PEST.

We estimated the sensitivity and specificity of the EARP

questionnaire using these substitute answers. The sub-

jects’ written consent was obtained according to the

Declaration of Helsinki, and the study was approved by

the Leeds (East) Research Ethics Committee.

Our results indicated that the sensitivity and specificity

of the questions in the CONTEST study that were con-

cordant with those in the EARP questionnaire were

79.5% and 35.5%, respectively (Table 1). These figures

are similar to those obtained with the other questionnaires

tested in this study.

The EARP was not tested directly in our patients, al-

though it was shown in the original Italian population to

be fast, taking only 2 min (1.5) min [mean (S.D.)]. This is

considerably shorter than the time reported for the

Psoriatic Arthritis Screening and Evaluation (6 min) [2],

and there is no indication of the time for completion in

the publications describing the PEST and the Toronto

Psoriatic Arthritis Screen. In conclusion, the EARP

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questionnaire may have acceptable sensitivity, although

specificity is still low, similar to that of other screening

tools.

Rheumatology key message

. The Early Arthritis for Psoriatic Patients question-naire is another PsA screening tool with similar sen-sitivity and specificity to other screening tools.

Acknowledgements

We would like to acknowledge the CONTEST collabor-

ation that collected the data used in this analysis.

Details of this collaboration can be found in Coates

et al. [7].

Funding: No specific funding was received from any

funding bodies in the public, commercial or not-for-profit

sectors to carry out the work described in this manuscript.

Disclosure statement: The authors have declared no

conflicts of interest.

Noemi Busquets-Perez1, Helena Marzo-Ortega2,3,Dennis Mcgonagle2,3, Robin Waxman3 andPhilip Helliwell2,3, on behalf of the CONTESTcollaboration1Department of Rheumatology, Hospital General deGranollers, Granollers, Spain, 2Leeds Musculoskeletal

Biomedical Research Unit, Leeds Teaching Hospitals, Leeds,3Leeds Institute of Rheumatic and Musculoskeletal Medicine,University of Leeds, Leeds, UK.

Revised version accepted 11 September 2014

Correspondence to: Noemi Busquets-Perez, Department of

Rheumatology, Hospital General de Granollers, Av FrancescRibes s/n, 8400, Granollers, Spain.

E-mail: noemibp76@hotmail.com

References

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2 Haroon M, Kirby B, FitzGerald O. High prevalence of

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7 Coates LC, Aslam T, Al Balushi F et al. Comparison of

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TABLE 1 Comparisons of questionnaires and Early Arthritis for Psoriatic Patients English translated questionnaire

nTrue

positiveFalse

positiveTrue

negativeFalse

negative Sensitivity Specificity AUC (95% CI)

PASE 195 35 91 57 12 0.745 0.385 0.594 (0.505, 0.683)PEST 195 36 93 55 11 0.766 0.372 0.610 (0.516, 0.704)

ToPAS 195 36 104 44 11 0.766 0.297 0.554 (0.455, 0.653)

EARP 182 35 89 49 9 0.795 0.355 0.634 (0.542, 0.726)

The information given about PASE, PEST and TOPAS proceeds from an earlier publication, the CONTEST study [7]; this

information has been reproduced with permission from John Wiley and Sons: Coates LC, Aslam T, Al Balushi F et al.

Comparison of three screening tools to detect psoriatic arthritis in patients with psoriasis (CONTEST study). Br J Dermatol2013;168:802�7 [7]; ! British Association of Dermatologists. Only the EARP data are novel. PEST: Psoriasis Epidemiology

Screening Tool; ToPAS: Toronto Psoriatic Arthritis Screen; PASE: Psoriatic Arthritis Screening and Evaluation; EARP: Early

Arthritis for Psoriatic Patients; AUC: area under the curve.

2 www.rheumatology.oxfordjournals.org

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